title: Indole-3-acetic acid biosynthesis in the biocontrol strain Pseudomonas fluorescens Psd and plant growth regulation by hormone overexpression.
abstract: Pseudomonas fluorescens is an important biological component of agricultural soils that bestows a number of direct and indirect beneficial attributes to the plants. We analyzed the biocontrol strain P. fluorescens Psd for indole-3-acetic acid (IAA) biosynthesis and studied the effect of its consequent manipulation on its plant-growth-promoting (PGP) potential. While the indole pyruvic acid (IPyA) pathway commonly associated with PGP bacteria was lacking, the indole acetamide (IAM) pathway generally observed in phytopathogens was expressed in strain Psd. Overexpression of IAM pathway genes iaaM-iaaH, from Pseudomonas syringae subsp. savastanoi drastically increased IAA levels and showed a detrimental effect on sorghum root development. On the other hand, heterologous expression of the indole-3-pyruvate decarboxylase/phenylpyruvate decarboxylase gene (ipdC/ppdC) of the IPyA pathway from the PGP bacterium Azospirillum brasilense SM led to enhancement of the IAA level. A more favorable effect of this recombinant strain on sorghum root growth and development suggests that metabolic engineering could be used to generate strains with improved PGP function.
authors.affiliation: Department of Genetics, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India. mandira.malhotra@gmail.com
authors.forename: Mandira
authors.initials: M
authors.lastname: Kochar
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Upadhyay
authors.forename: Sheela
authors.initials: S
authors.lastname: Srivastava
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D007210:Indoleacetic Acids / Q000378:metabolism*; D010572:Pest Control, Biological; D010935:Plant Diseases / Q000382:microbiology; D010937:Plant Growth Regulators / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development / Q000382:microbiology; D011551:Pseudomonas fluorescens / Q000235:genetics / Q000378:metabolism*; D045868:Sorghum / Q000254:growth & development / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; C030737:indoleacetic acid; C068832:indolepyruvate decarboxylase; D002262:Carboxy-Lyases